# 自定义用户认证系统的后端：实现多账号登录
from django.contrib.auth.backends import ModelBackend
import re
from users.models import User
from django.conf import settings
from . import constants
from itsdangerous import TimedJSONWebSignatureSerializer as Serializer

from itsdangerous import BadData
def check_verify_email_token(token):
    """反序列化token获取到user
    :param token: 序列化后的用户信息
    :return:user
    """
    s = Serializer(settings.SECRET_KEY, constants.VERIFY_EMAIL_TOKEN_EXPIRES)
    try:
        data = s.loads(token)
    except BadData:
        return None
    else:
        # 从data中提取user_id和email
        user_id = data.get("user_id")
        email= data.get("email")
        try:
            user = User.objects.get(id=user_id,email=email)
        except User.DoesNotExist:
            return None
        else:
            return user

def generate_verify_email_url(user):
    """
    商城邮箱激活链接
    :param user: 当前登录的用户
    :return: token
    """
    s = Serializer(settings.SECRET_KEY,constants.VERIFY_EMAIL_TOKEN_EXPIRES)
    data = {"user_id":user.id,"email":user.email}
    token = s.dumps(data)
    return settings.EMAIL_VERIFY_URL+"?token="+token.decode()



def get_user_by_account(account):
    """
    通过账号获取用户
    :param account: 用户名或者手机号
    :return: user
    """
    try:
        if re.match(r"^1[3-9]\d{9}$", account):
            # username==手机号
            user = User.objects.get(mobile=account)
        else:
            # username=="用户名"
            user = User.objects.get(username=account)
    except User.DoesNotExist:
        return None
    else:
        return user
class UsernameMobileBackend(ModelBackend):
    """自定义用户认证系统的后端"""
    def authenticate(self, request, username=None, password=None, **kwargs):
        """
        重写用户认证的方法
        :param request:
        :param username:用户名或者手机号
        :param password:明文密码
        :param kwargs: 额外参数
        :return: user
        """
        # 查询用户
        user = get_user_by_account(username)
        # 如何可以查询到用户，还需要进行密码校验
        if user and user.check_password(password):
            # 返回user
            return user
        else:
            return None


